Building structures



April 12, 1955 H. M. PONT BUILDING STRUCTURES Filed Feb. 12, 1951 HenriMac (am e PON'T IN VENTOH BY M.)

United States Patent BUEDING STRUCTURES Henri Maclaine Pont, Voorburg,Netherlands Application February 12, 1951, Serial No. 210,510

Claims priority, application Netherlands March 9, 1950 6 Claims. (Cl.108-1) The invention relates to a large span roof of the elastic typedescribed in applicants copending applications Nos. 759,584 and 759,585both filed on July 8, 1947, and now Patents 2,545,556 and 2,592,465respectively and comprising self-adjusting supports at the corners ofthe roofed space only, resiliently flexible curved rafter principalswhich bear upon the supports, meet in the top of the roof and are turnedwith their concave sides towards the inside, eaves-cables provided roundabout the roof on the level of the lower ends of said rafter principals,networks provided in the roofing planes between said principals and saideaves-cables and a roof covering supported directly by said roofingnetworks.

The invention has for a primary object to so improve such elastic roofs,which have already the tendency to restore by their weight the state ofequilibrium, as to obtain an equal distribution of the stresses set upby forces from the outside, say by the wind, in all sides of the roofs.It consists in that the self-adjusting supports include movablesupporting elements and stationary supporting members, the lower end ofeach rafter principal being hingedly connected to such a movablesupporting element by a ball joint and each of said supporting elementshaving a curved sole-surface bearing on a stationary supporting member,which permits each movable element to perform a restricted rollingmovement in all directions on the supporting face of its stationarymember, the main axis of each movable supporting element containing thecenter of the corresponding ball joint, and each ball joint is situatedat a greater distance from the supporting face of the stationarysupporting member in any position of the supporting element differingfrom the position of preference than in said latter position, saidposition of preference being defined by the fact that only in thatposition the said axis of revolution is at right angles to thesupporting face of the stationary supporting member.

Movement of the supporting elements from the position of preferenceraises the roof and/ or tightens the eaves cables, so that the weight ofthe roof and/or the tension of the eaves cables tend or tends to keepthe supporting elements in their positions of preference or to bringthem back into said positions. Moreover the rafter principals are freeto adjust themselves to the stresses exerted in the roof structure andtherefore they will assume positions in which the stresses will beequally distributed round about the roof, even when the forces from theoutside are exerted on one side of the roof only.

If the supporting elements are placed on supporting faces which are inan inclined plane sloping towards the outside and, transverse to suchplane, are at right angles with the vertical plane containing the curvedrafter principals, they are able to exert horizontal stretching ortautening forces on the elastic roof, which forces are dependent on theweight of the roof.

In an embodiment of the invention balls may be interposed between thesole-surface of each supporting element and the supporting face of eachstationary member. This embodiment has the advantage, that the pressureexerted by a supporting element on a supporting face is distributed overa great number of balls, that means is not concentrated in one singlepoint any more.

These and other features of the invention will be elucidated by means ofthe following description and the accompanying drawing, in which:

Fig. 1 is a diagrammatical perspective view of a roof of large spansupported in its corners by movable self- "ice adjusting supportingelements, which bear upon inclined supporting faces of stationarymembers,

Fig. 2 is a diagrammatical view of one of the movable supportingelements of Fig. 1 bearing on a horizontal supporting face in twodifferent positions,

Fig. 3 is a sectional view of a movable supporting element and acorresponding stationary supporting member, in which the element iscoupled with said member and the supporting face of the latter is madeelastic, and

Fig. 4 is a sectional view of another embodiment of the invention inwhich the supporting element is placed with its sole-surface on balls,which are adapted to roll on a curved supporting face.

Fig. 1 illustrates a roof of large span and elastic structure of thetype described in the copending U. S. specifications 2,545,556 and2,592,465. This roof, consisting of rafter principals 10, eaves-cables8', networks 8" and a roof covering 8, bears on corner supports, each ofwhich consists of a stationary supporting member 9 having an inclinedsupporting face 7, which is contained in a plane 7 sloping towards theoutside and directed, transversely of such inclined plane, at rightangles to the vertical plane 10' containing the curved rafter principal10 in question, and a supporting element 3 in the shape of a sphericalsector-like bearing with its spherical sole-surface 4 on said supportingface 7. The apex 2 of said supporting element is connected by a balljoint to the foot or lower end of the rafter principal 10. In theneutral position or the position of preference the angle d enclosed bythe main axis 6 of the supporting element 3 and the horizontal planeintersecting the vertical plane in the line 11 is equal to the angle Binclosed by said line 11 and the tangent 12 to the foot of the curvedrafter principal 10.

Fig. 2 illustrates on a larger scale a movable supporting element whichis similar to the element shown in Fig. 1. Said element has the shape ofa spherical sector-like portion and bears in this case with itsspherical sole-surface 4 on a horizontal supporting face 5 of thestationary supporting member. The distance between the apex 2 of theelement 3, said apex being the center of the ball joints, and any pointof the sole-surface 4 is smaller than the radius of said sole-surface sothat the supporting element is not a true sector but is only sector-likein appearance.

When a force is exerted in horizontal direction on the roof 8, forinstance by the wind, the supporting elements 3 perform a restrictedtrue rolling movement on the supporting face 5 and they are adjusted ina position, in which the sum of the forces exerted in horizontaldirection on the roof by said supporting elements is equal and contraryto the original force exerted on the roof.

Fig. 2 shows that in the case of the horizontal support the apex 2 israised, so that the roof 8 is lifted, when the supporting element 3 isrolled with its sole-surface 4 over the base 5. In this case thesupporting element 3 will be brought into a position, in which theresultant R of the force A, which is laterally exerted on the apex 2' ofthe supporting element and for instance is set up by the wind, and theweight G of the roof is directed towards the point of contact betweenthe sole surface 4 and the supporting face 5. Since the weight G isconstant the deviation from the position of preference, which is shownin Fig. 2 in continuous lines, will increase, when the lateral force Ais increased. In the position of preference the lateral force A has thevalue zero. Thus the supporting elements tend to bring the roof backinto its position of preference, in which position said roof is on itslowest level.

If the supporting element 3 is positioned on an inclined supportingsurface 7 as is illustrated in Fig. 1 the above described self-adjustingeffect of the supports of the roof will also be obtained. In that casethe apex 2 of a supporting element wil move away from the apices ofadjacent supporting elements during its downward rolling movement, saidrolling movement thus being counteracted by the stress set up in theeaves-cables, and said apex will move upwards during its upward rollingmovement, said latter movement thus being counteracted by the weight ofthe roof. In both cases, there will be generated a force which will tendto return the supporting element into its position of preference. Itwill be apparent that in the case of the sloping support of thesupporting elements these elements have a permanent tautening action onthe roof structure.

In Fig. 3 the supporting element 3 rests with its sole surface 4 on asupporting surface in the form of a plate 13, which is supported on themarginal portion only. This plate is a little bent by the weight to besupported, so that the contact between the supporting element and thesupporting face has the shape of an area instead of being a point only.The specific pressure is considerably reduced by this measure. The plate13 operates as the membrane of a drum.

In order to prevent sliding movement of the supporting element, saidelement 3 may be provided with a recess 14 and the base may have a peg15, which engages said recess. The peg is provided with a head 16forming an abutment for an annular rib 17 at the edge of said recesswhich delimits the rolling movement of the supporting element from itsposition of preference. In order to keep the supporting surface freefrom dirt and dust the supporting element 3 is provided with a screen 18suspending from the circumference of the sole-surface of the supportingelement.

In Fig. 4 the supporting element 3 is positioned on balls 19, which aresupported by a curved supporting surface 20. Also in this case, in whichthe supporting element performs both a rolling movement and atranslatory movement, the conditions must be so chosen, that the apex ofthe supporting element always moves in a direction having a componentpointing from the supporting surface, when the supporting elernent isrolled from its position of preference. The use of balls gives morepoints of contact that the direct support, so that the specific pressureis reduced.

A curved supporting surface may also be used in the embodiment accordingto Figs. 1, 2 and 3. it is not necessary that the sole-surfaces of thesupporting elements are spherically curved. Said sole-surfaces may alsobe curved otherwise and may for instance have the shape of a parabola,an ellipse, a hyperbola or the shape of a portion of the surface ofanother body of revolution.

What I claim is:

l. A roof of large span comprising, in combination, self-adjustingsupports at the corners of the roofed space only, resiliently flexiblecurved rafter principals which bear upon the supports, meet in the topof the roof and are turned with their concave sides towards the inside,eaves-cables provided round about the roof on the level of the lowerends of said rafter principals, networks provided in the roofing planesbetween said principals and said eaves-cables and a roof coveringsupported directly by said roofing networks, said self-adjustingsupports including movable supporting elements and stationary supportingmembers, a ball joint hingedly connecting the lower end of each rafterprincipal to a movable supporting element, each of said supportingelements having a curved sole surface bearing on a stationary supportingmember, which permits each movable element to perform a restrictedrolling movement in all directions on the supporting face of itsstationary member, the main axis of each movable supporting elementcontaining the center of the corresponding ball joint and each balljoint being situated at a greater distance from the supporting face ofthe stationary supporting member in any position of the supportingelement differing from the position of preference, the position ofpreference being defined as the position of the supporting element whenthe said axis is at right angles to the supporting face of thestationary supporting member.

2. A roof of large span as claimed in claim 1, characterized in that arecess opening towards the sole surface of the'movable supportingelement is formed in said element andis provided at its edge with anannular rib narrowing said opening and a peg having an enlarged headcarried by the supporting face of the stationary supporting member andhaving its head received in said recess of the movable supportingelement, said annular rib surrounding the opening of the recess abuttingthe head of said peg, when the movable supporting element is deviatedmaximally from its position of preference.

3. A roof of large span as claimed in claim 1, characterized in thatballs are interposed between the sole surface of the movable supportingelement and the supporting face of the stationary member.

4. A roof of large span as claimed in claim 1, characterized in that thesupporting face of each stationary member is contained in an inclinedplane sloping downwardly towards the outside and at right anglestransverse of said inclined plane, with the vertical plane containingthe corresponding curved rafter principal.

5. A roof of large span as claimed in claim 1, characterized in that thesupporting face of the stationary member is constituted by a flexibleplate having a circuiinference and being supportedon said circumferenceon y.

6. A roof of large span as claimed in claim 1, characterized in that thesupporting face of the stationary member is curved.

References Cited in the file of this patent UNITED STATES PATENTS311,338 Lindenthal Jan. 27, 1885 592,852 Westwood Nov. 2, 1897 2,014,643Bakker Sept. 17, 1935 2,208,872 Ropp July 23, 1940 2,359,036 HarperSept. 26, 1944 2,545,556 Pont Mar. 20, 1951 FOREIGN PATENTS 266,568Italy 1929 367,847 Italy 1939

